This invention relates to a surgical instrument for clearing obstructions in ducts, particularly but not exclusively arteries.
A number of techniques are known for clearing obstructions in coronary arteries. These include by-pass surgery, the use of a xe2x80x9cballoonxe2x80x9d to expand the arterial wall in the region of the obstruction, the use of a cutter passed along the artery to remove the obstruction and the use of a drill which is also passed along the artery to pulverize the obstruction. By-pass surgery is a major operation and is expensive. The use of surgical instruments in the above-described alternate methods involves the risk that the instrument which is passed along the artery will puncture the arterial wall during use or during passage along the artery to the location at which the obstruction is to be cleared. Additionally, the use of a drill which pulverizes the obstruction involves the risk of the pulverized material lodging in another part of the body and causing damage there.
It is an object of the present invention to provide a surgical instrument for clearing obstructions in ducts in which the above described problems can be obviated or mitigated.
According to the present invention, there is provided a surgical instrument for clearing obstructions in ducts, comprising a body having a forward end defined by a sleeve, a cutter member mounted in the sleeve for rotation relative thereto, and elongate flexible drive means connected to the cutter member and extending rearwardly of the body to enable rotation of the cutter member, wherein the cutter member includes an outer cutting edge cooperating with the sleeve to produce a circular cut upon rotation of the cutter member in use.
With the above-described surgical instrument, the sleeve assists in preventing accidental penetration of the wall of the duct by the cutter member during use or when being maneuvered into position for use. The instrument can be used percutaneously as a non-operative device.
It is preferred for the cutter member to include a blade having a helical outer cutting edge, and particularly preferred for the cutter member to take the form of a screw whose outer surface cooperates with the sleeve to produce the circular cut. Such screw also serves, upon rotation, to transport material from the obstruction into the body of the instrument. Conveniently, a chamber is provided in the body to receive such material which can then be completely removed from the duct upon removal of the body of the instrument therefrom Thus, the material which has been cleared away is completely removed from the duct.
In a particularly preferred embodiment, the forward end of the cutter member protrudes through the forward open end of the body. To reduce the risk of such cutter member accidentally penetrating the wall of the duct in use or whilst it is being maneuvered into position along a duct, it is convenient for the forward end of the cutter member to be relatively blunt. However, in the case where the cutter member takes the form of the screw, it is preferred for it to have a tapered forward end protruding from the forward end of the sleeve. Such tapered forward end can then serve to penetrate the obstruction and draw the body along the duct upon rotation of the screw. This is considered to be a particularly effective way of advancing the body along the duct since it does not require the body of the instrument to be pushed along the duct.
The elongate flexible drive means preferably takes the form of a cable or the like mounted for rotary movement within a relatively fixed, flexible sleeve. The flexible sleeve preferably takes the form of a hollow helical spring which is preferably provided with a continuous cover or sheath to provide a smooth external surface for ease of passage along the duct to be cleared.
The body and the cutter member may be provided with a passage extending axially therethrough so that the body and cutter can be mounted on an elongate guide wire or the like. In use, it will be appreciated that such guide wire can be passed along the duct relatively easily because of its small diameter, and then the body can be passed along the duct whilst being guided by the wire so as to facilitate safe passage along the duct to the site of the obstruction. The surgical instrument will normally be used whilst the patient is conscious, and its progress along the duct can be monitored by x-ray inspection.
In the case of surgical instruments according to the present invention designed for clearing arterial obstructions, the external diameter of the body will be in the region of 2 to 4 mm. The instrument can be used for bioducts generally.
Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which